Process of making smokeless explosives



(No M0331.) 2 sheets-sheet 1.

P. G. '3v P53. DU PONT. PROGBSS 0F MAKING SMOK-ELESS EXPLOSIVES.

No. 503,533.. Patented Aug. 22, 1393.

Lf' Lf 3 gmlml (No Model.) 2 Sheets-Sheet 2.

F. G. v P. s.' DU PONT. PROCESS OP MAKING SMOKELESS BXPLOSIVES.

No. 503,583. Patented Aug. 22, 1893.

M j.. if

AUNITED STATES PATENT OFFICE.

FRACIS G. DU PONT AND PIERRE S. DU PONT, F W-ILMINGTON DELAWARE. 'A

PROCESS OF MAKING SMOKELESS EXPLOS'IVES.

` SPEQIFICATIN forming part of Letters Patent No. 503,588, dated August 22, 1893.

Application filed December 21, 1892. Serial No. 4515,901. (No specimens.)

To all`w7wm it may concern.-

Be it known that we, FRANCIS G.,DU PONT and PIERRE S. DU PONT, citizens of the United1 States, residing at Wilmington, in the county,

of New Castle and State of Delaware, have invented certain new arid useful Improvementsin Explosives; and we do hereby declare the following to be'a full, clear, and exact description of the invention, such as will enable others'skilled in the art to which it appertains to make and use the same. Y

Our invention relates to improvements in explosives to be used in small arms, large guns, as a bursting charge for shells, or for any other explosive use to which it may be suited,'and it consists in an improved process for producing an explosive from nitro-cellulose, consisting in granulating the nitro-cellulose by agitating therewith, when suspended in a liquid, a suitable solvent of the same m proper proportions, which wllbe hereinafter fully described, and particularly pointed out in the claims. "I

The main object of our invention is to produce an explosive which will be smokeless, or nearly so; which, while imparting a high muzzlevelocity tothe projectile, will not cause undue pressure in the gun barrel at the moment of tiring, and which can be easily and safely handled-and stored.

Nitro-cellulose in some of its forms, usually that of gun cotton, has frequently1 been used as the basis of smokeless powders, because it unites in itself so many of the qualities which good smokeless powders must possess; that is to say, it is very stable when properly prepared, burns or explodes with very little.

smoke, possesses great power as an explosive, and is not hydroscopic enough to impair its keeping qualities. The explosive force of gun cotton, or other nitrated fiber, when used by itself is so great, however, and the dnculties of securing an even rate of combustion so hard to overcome, that its use by itself is dangerousin lire arms.

-Many attempts have been made to control or diminish the explosive force of gun cotton,

while preserving all of its advantageous proporties. These attempts have in general proceeded along three lines,viz: First: That of subjecting the gun cotton to great pressure,

' proper proportions,

by which all air spaces, in which the explosive gases might collect, are removed from it, and it is rendered solid and compact. Second: That of mixing with the gun cotton certain substances which lessen its rate of combustion, the substances added being less violent in explosivo force than the gun cotton. For this purpose nitro-benzole, nitro-naphthaline, camphor, and the high boiling ketones and acetates have been used. Third: The solvents of gun cotton. which have been added may be entirely evaporated, leaving the gun cotton in a state resembling eelluloid, in which its condition is changed from the fibrous to the amorphous state, in lwhich latter state it is more compact than the original gun cotton.

Our invention belongs to the classes above specified, but it differs from all other processes now known or used in that the gun cotton is treated in a wet way, by -suspending it in a fiuid and mixing with it a suitable solvent, which produces a granular condition hereinafter described. l

We have discovered that the various solvents of gun cotton, especially the nitro-derivatives of the aromatic group, have a tendency, when mixed with a duid in which inely divided gun cotton is suspended, to4 seize the gun cotton and leave-the water clear, forming in the water a more or less coherent mass; and that when a suitable solvent is added m and the mass is even slightly agitated, a well defined granular condition is the result, the solvent collecting the particles of nitro-cellulose into grains, vand forming a coating around 'the same. These grains, after they have undergone a process third of the process of rotation, or by rotation in a barrel in an atmosphere of steam, in which case the removal of the excess of solvent and water contained in the grains will take place at the same time as the rotation, become sufficiently firm to be graded according to size, and constitute a valuable smokeless powder, the violence of whose explosive action c an be diminthe duration of the abovey ished by varying iprocesses, or it may be still further dim'inished by the addition of a substance to moderate its action. We have found nitrated rosin and nitrated turpeutine especially suited for thispurpose, and we add them in the mauner and proportion which will be hereinafter stated.

In the drawings accompanying and forming a part of this application, we have represented the apparatus which we usein carrying out our process.

FigureLwhich is taken on the .line a; Fig. 1*, looking in the direction of the are. row, illustrates the churn in which the mixture of the gun cotton with the solvent takes place, Fig. 1 being a sectional view of the same, and Fig. 2 being a represen tation of the rotating barrel in which the grains formed in the churn shown in Fig. 1 are hardened and rounded, and thus fitted for use. 1t is taken on the line y 'y Fig. 2". Fig. 2 is a view taken on the line z z Fig. 2, looking in the direction of the arrow. It shows the Adouble series of apertures in the inner bulkhead of the barrel, and also the series of cycloidal chutes which conduct the water of condensation, received through the outer series of apertures in the bulkhead, to the apertures in the central pipe forming the axis of the barrehby which pipe the said Y water is conveyed away.

Before proceeding with a description of our process, we will descri-be the apparatus used in carrying it out. l

Referring to Figs. 1 and 1, A represents a churn, in which, on a shaft B, are rotated the .blades b, each of which' is formed with a notched outer surface to promote currents from side to side in the contents of the churn during rotation. Steam inlet pipes C are provided which are relativelysmall in diameter, so that the steam will be well distributed through the contents of' the churn, and asin'- gle steam outlet pipe D, which leads to the refrigerating coils E, where the vapors which it conducts may be condensed. An opening F is provided for the admission of material, and an opening C to aid in tlushiugpth'e interior of the churn when desired. Test cocks 1 1 are also provided, in order that the condition of the contents of the churn may at any time be inspected.. v

In Figs.4 2 and 2 the rotating barrel is represented in which the grains of explosive produced in the churn just described are hard ened and prepared for use. This barrel, H, is provided with a tubular axis I, journaled in the supports it', to which axis steam is couducted by the pipe 2, and from which steam is conveyed by the pipe 3. The barrel is designed to facilitate the escape of both water and steam from the interior of the same, the steam carrying olf the solvent used, and to this end is formed with an inner bulkhead K, which is placed in close proximity to the bulkheadHRof the barrel. In the inner bulkhead are formed two series of apertures, one

around its periphery 8 for the separation of water from the contents of the barrel, and one near its center 9 for the escape of steam from the same. Between the two bulkheads K and H2 is arranged a series of cycloidal guides or chutes L, all of which converge toward the central artis.

In the operation of the barrel, steam is adbin the central axis, and passes out through the apertures 8 and 9 in the bulkhead K, and

ing with it, as will be hereinafter explained, the excess of the solvent found with vthe grains of explosive. Water of condensation., as fast as formed, passes through the lower series of apertures in the bulkhead K at ,the lower stage ofthe revolution ot the barrel into the space between said bulkhead K and bulkhead H2, and is conducted by the cycloidal chutes toward the axis of the barrel, then passing out through the apertures 6 formed at this point.

in the churn A about ninety liters of a suitable liquid, such as water, which may either be pure, or mixed with any salt. When water is used, we sometimes dissolve in it chloride of calcium, common salt, saltpeter, or other salt, as we can thus modify in many ways the characteristics of the grains formed. The ,proportion in 'which these ingredients are added depends somewhat upon which one is used. In the case of salpeter, about a half saturated solution will answer very well, or even one of greater strength, say a saturated solution at a temperature of 60, Fahrenheit. We add to the liquidl about six kilogramspf finely divided gun cotton, beating it up with ture has taken place, and the gun cotton is uniformly suspended in the liquid. When as nitro-benzole, to the extent ofI about three times the weight of the gun cotton. By the ac tion of the solventnpon the suspeiided gun cotton aplastic, oceulent mass is f ormed,wh ich by slight agitation becomes granulated. When the agitation in the churn is now continued, a well defined granular product is procollecting theparticlesofgun'cotton,and forming them into grains, which are as yet somewhat soft and pul py as they contaimconsiderthe particles of gun cotton suspended, and thus enabling the 'action of the solvent to be carried on uniformly upon all the particles of steam' may be admitted through the bottom of the churn, and this, as itpasses out through the refrigerating-coils, carries with it a portion of the solvent, which is recovered in the said coils. This action of the steam is not,

however, essential gto. 4the production of the thence through the axis I and pipe 3, carry-l the water in the churn 'until a thorough mix-l this has been accomplished, we add to the, mixturea suitable solvent'of gun cotton, such I duced,the solvent (in this case nitro-benzole) able water, and as there is an excess of solvent. The agitation aids th'e granulation by keeping r gun cotton in thechurn. v During this action,-

mitted to its interior through the aperture 5" Proceeding now with our process, we place IIO and may be omitted without detriment to the product., Y

Instead of using nitro-benzole to produce the granulation nitro-toluol or nitro-Xylol may be used, or other solvents. The solvent used, however, must not be miscible to any great extent in the liquid in which the gun cotton is suspended, as if it is so miscible, it will not leave the liquid readily and form the desired granulation. The suitability of the solvent is thus determined. We do not conne ourselves to the proportions mentionedof the gun cotton and solvent, although vthese have been found to give good' results, as the proportion may be altered and still a good granulation is obtained. The contents of the churn are'now removed, and the grains are placed. in the revolving barrel shown in Figs. 2 and 2". By rotating the barrel fora greater or less time without the admission of steam,'the. grains are compacted and rounded. The barrel is then partially tilled with water, and rotated in such a direction as to prevent the cycloidal chutes from carrying othe water, steam being admitted,'and"the rotation continued until a further portion of the solvent is carried olf. When this action has proceeded sui'- cientlyfar, the direction of rotation is changed, and the ow of steam continued untilthe excess of solvent is entirely removed. The action of this latter process, namely the rotaltionin an vatmosphere of steam, is to increase to a very great degree the density of the grain, and to round and compact the same, fittingit for its destined use as an explosive.

The density' and also the size of the grainy formed may be varied by ehangingthe proportions of the ingredients, and by altering the length of time ofthe preliminary rolling in the revolviugbarrel. The principle at thel root of the matter v,is this:` If `the original grains formed in thechurn have a large quantity of nitro-benzole, or other solvent use'd; they will be quite plastic, and during the preliminary rolling in the barrel will tend to I gather up any loose material which may happen to be among the grains, thus becoming' larger; while if the proportionfof the nitro-benzole, or other solvent, to the gun cotton in the churn be made -smaller, the grains formed will be less plastic, and will be apt to remain nearly the same size as when produced in the churn for the reason. that they are less plastic, and v-have more consistence, and -consequentl-y do not tend to pick up material Aas they will itv more plastic. Furthermore,the quantity of solvent used in proportion to the l. 'gun'cotton has some intluence upon the preliminary-grains in the churn, the grains in the churn always being larger when a greater percentage is used from the fact that the combination is of a more plastic nature, and tends to unite in larger particles.V We may also remove thcgrain at any stage of the before-l mentioned processes, and evaporate the sol# vent by boiling this grain with water in the orln o'rdcrthat the grains formed by the above process may be tcm pered in explosive force to any degree required, we dissolve 1n the solvent used in the granulation process from two and one-half to ten per cent. of a moderating agent, and nd especially adapted for this purpose nitrated rosin or nitrated turpentine, 't'. e., rosin or Venice turpentiue treated with nitric acid', though we do not confine ourselves to the use of these substances, or to the proportions mentioned. Instead of adding the moderating agent in the manner described, it may be added to the grain after it is finished,-by means of solution in a volatile solvent, or in any other manner.

While we have described the gun cotton as being dilnsed in water, it is evident that any other fluid which will causel a better or as good adistribution of the particles of gun cotton in the churn may be used instead, and we do not confine ourselves to the use of water as a suspending liquid; nor do we confine ourselves to the use of the particular form of nitro-cellulose known as gun cotton. We also do not confine ourselves to the particu-lar solvents mentioned, or to the exact proportions in which they areadded, or to the particular apparatus employed.

What we claim as new, and desire to secure by Letters Patent, ils--v 1. The herein described process of making a smokeless explosive,whichvconsists in sus-4 pending nitro-cellulose in aliquid nota solvent of the same, granulating the nitro-cellulose by agitating therewith in proper proportions a suitable solvent not miscible to any great extent in the liquid used to'suspend the nitro-cellulose, and solidifying'the grains thus formed, substantially as described.

2. The herein described Vprocess o f making a smokeless explosive, which `consists in suspending nitroecellulose in a liquid not a solv- 1 ent of the same, gran'ulatin the nitro-cello'- lose byagitating therewith 1n proper proportions a suitable solvent-not miscible to any great extent inthe liquid used to suspend the Vnitro-cellulose, and solidifying the grains thus lformed by heat, substantiallyas described.

3. The herein described process of producing a smokeless explosive, which .consists 1n suspending nitro-cellulose in a hquid not a solvent of the same, granulating the nitrocellulose by agitating therewith'ln proper proportions a suitable solvent.fnot"miscible to any great extent in the liquid used to'suspend the nitro-cellulose, and solidifying the grains thus formed -by agitation in anatmos'- phere -of steam, substantially as described.

4. The herein described process of producing a smokeless explosive, which consists in suspending nitroscellulose in a liquid not a solvent 'of the same, granulating the nitrocellulose by agitating therewith in proper prograins thus formed by rotation, and further l steam, substantially as described.

solidifying the grains by rotation in an Yatmosphere of steam, substantially as described.

n G. The herein described process of produclng a smokeless explosive, which consists in suspending nitro-cellulose in a liquid lnot. a solvent of the same, granulatin g the nitro-cellulose by agitating therewith in proper proportions, accompanied by injection of steam, a suitable solvent not miscible to any great extent in the liquid used to suspend the nitrocellulose, and solidifying the grains thus formed by agitation in an atmosphere of 7. The herein described process of producing a smokeless explosive, which consists in suspending nitro-cellulose in a liquid not a solvent of the same, granulating the nitro-cellulose by agitating therewith inproper proportions a suitable solvent not miscible to any great extent in the liquid used to suspend the nitro-cellulose, soliditying the grains thus f formed, and moderating the action of the same by the addition, during the above operation, of a suitable moderating agent, substantially' as described. v

8. The herein described p ro'cess of lproducing a smokeless explosive, which consists iny suspending nitrocellulose .in a liquid not a solvent of the same, granulating the nitro-cellulose by agitating therewith in proper pr()- portions a suitable solvent not miscible to an)7 great extent in the liquid used to suspend the nitro-cellulose, and in which is' dissolved a moderating agent, andgsolidifying the grains thus formed, substantially as described.

9; The herein described process of producing a smokeless explosive, which consists in suspending nitro-celluloseQ in a liquid, such suspending,` nitro-cellulose in a liquid not a solvent of the same, granulating the nitro-cellulose by agitatiug therewith in proper proportions, during injection of steam, a suitable solvent not miscible to any great extent in the liquid vused to suspend the nitro-cellulose and in which is dissolved a moderating agent, and solidifyin g the grains thus formed by rotation, and afterward by rotation in an atmosphere of steam, substantially as de# scribed. A Y

. In testimony whereof we aix oursignatures in presence of two witnesses. v v v FRANCIS G. DU PONT. PIERRE S. DU PONT. Witnesses: l

J. H. HOFFECKER, Jr., FRANK M. SMITH. 

